Using MODIS albedo as input in WRF with Noah-MP

[seti]

Dear WRF Support Team,

I am using WRFV4.8.0 with the Noah-MP land surface model (sf_surface_physics = 4), and I would like to replace the default albedo with satellite-derived MODIS albedo for a 5-day simulation.

My plan is to download MODIS albedo corresponding to my simulation period, regrid it to the WRF domains, and use these values to modify the albedo field in the WRF input files.

However, I am not sure about the correct procedure for Noah-MP. In particular, I would appreciate your advice on the following questions:

1. Is directly replacing the ALBEDO field in wrfinput_d0* with MODIS-derived albedo an appropriate approach when using Noah-MP?
2. If I modify ALBEDO in wrfinput, will Noah-MP actually use these prescribed values during the simulation, or will it recalculate albedo after initialization?
3. If Noah-MP recalculates albedo, what is the recommended method to ensure that my MODIS-derived albedo is actually used throughout the 5-day simulation?
4. Do I need to modify ALBBCK, ALBEDO12M, or another variable instead of (or in addition to) ALBEDO?
5. Are any specific namelist options required, such as usemonalb, sst_update, or settings in the &noah_mp section?
6. Since Noah-MP uses opt_alb for the ground/snow surface albedo treatment (opt_alb = 1 for BATS and opt_alb = 2 for CLASS), how does this option interact with externally prescribed MODIS albedo? Would either option overwrite or modify the MODIS albedo during the simulation?

My simulation is for a winter period, so snow is present in parts of the domain. Therefore, I would also like to understand whether MODIS surface albedo can be prescribed directly in snow-covered grid cells, or whether Noah-MP will recompute the effective surface albedo based on its snow-albedo parameterization.

My main goal is to use time-specific MODIS albedo instead of the default/climatological albedo while keeping the treatment physically consistent with Noah-MP.

I would greatly appreciate any guidance on the recommended workflow.

Best regards,

 

[seti]

Dear WRF Support Team,

I am using WRFV4.8.0 with the Noah-MP land surface model (sf_surface_physics = 4), and I would like to replace the default albedo with satellite-derived MODIS albedo for a 5-day simulation.

My plan is to download MODIS albedo corresponding to my simulation period, regrid it to the WRF domains, and use these values to modify the albedo field in the WRF input files.

However, I am not sure about the correct procedure for Noah-MP. In particular, I would appreciate your advice on the following questions:

1. Is directly replacing the ALBEDO field in wrfinput_d0* with MODIS-derived albedo an appropriate approach when using Noah-MP?
2. If I modify ALBEDO in wrfinput, will Noah-MP actually use these prescribed values during the simulation, or will it recalculate albedo after initialization?
3. If Noah-MP recalculates albedo, what is the recommended method to ensure that my MODIS-derived albedo is actually used throughout the 5-day simulation?
4. Do I need to modify ALBBCK, ALBEDO12M, or another variable instead of (or in addition to) ALBEDO?
5. Are any specific namelist options required, such as usemonalb, sst_update, or settings in the &noah_mp section?
6. Since Noah-MP uses opt_alb for the ground/snow surface albedo treatment (opt_alb = 1 for BATS and opt_alb = 2 for CLASS), how does this option interact with externally prescribed MODIS albedo? Would either option overwrite or modify the MODIS albedo during the simulation?

My simulation is for a winter period, so snow is present in parts of the domain. Therefore, I would also like to understand whether MODIS surface albedo can be prescribed directly in snow-covered grid cells, or whether Noah-MP will recompute the effective surface albedo based on its snow-albedo parameterization.

My main goal is to use time-specific MODIS albedo instead of the default/climatological albedo while keeping the treatment physically consistent with Noah-MP.

I would greatly appreciate any guidance on the recommended workflow.

Best regards,

@Ming Chen